> 0.181 was running fine on here a few days ago. About the only thing I can think of> that's changed is that the 10.12.3 update to OS X was pushed down recently.> Unfortunately, I don't recall if I ran 0.181 after that was installed or not, so> can't give a direct comparison.

This hadn't occurred to me when I made the original post, but it may be relevant.

I did a clean install of 10.12.2 about three weekends ago. When I say 'clean install', I mean it: it was a total reinstall of the OS and applications from scratch. No Time Machine recoveries, no 'let's sync your Mac' stuff... Just a nuke and manual rebuild.

Now, one of the few things that was brought over from manual backups was MAME 0.181. The binary for this had been built under Yosemite (10.10.5, IIRC; I skipped El Capitan entirely). Under 10.12.2, it ran without issue.

I built MAME 0.182 after the 10.12.3 update, and I don't believe that I ever ran the 0.181 binary after that update. Unfortunately, I overwrote my 0.181 binary with 0.182 because on first run my 0.182 binary looked good... But if I'd run it a second time I would have known not to overwrite. Dumb move on my behalf, but that's my fault.